Mmm-Mmm-Mealworms! Almost all passerine (perching) birds eat insects, and mealworms are high on their list of favorite snacks. Put out a few mealworms for your birds and they’ll be gobbled up before you can say “The early bird gets the …”
Oh, you thought they were just for bluebirds? Nope. Chickadees, titmice, sparrows, woodpeckers, robins, wrens, orioles, tanagers, warblers, blue jays, starlings – you name it. Pretty much any bird that eats insects will eat mealworms—in bulk! (Chickens too, in case you’re thinking of getting into the backyard chicken movement.)
Exactly What Is a Mealworm?
Mealworms, which are also known as ‘yellow mealworms’ or ‘golden grubs’ are not actually worms. What they really are is the larval stage of the Tenebrio molitor darkling beetle, one of a huge family of black beetles. This one is a grain eating insect that lives on stored grain. The larvae are an inch to inch-and-a-half long and are quite harmless.
Why Feed Mealworms to Birds?
Mealworms are high in both calories and proteins, which make them great supplements to give your birds in both winter when insects are hard to find and in spring, when nestlings need to grow strong muscles before leaving the nest.
They contain enough vitamins and minerals to rival beef and are available for birds in live and dried forms.
Note: Humans also snack on mealworms and you may see them in the grocery store. Don’t feed these human-food worms to birds – they may have unsuitable additives. (In case you’re wondering, mealworms are said to taste like nutty shrimp.)
How to Offer Mealworms
Dried mealworms can be mixed in with other bird food or served alone in any kind of feeder (I use an old cookie pan.)
Live mealworms can climb any rough surface, so pop them into a glass or smooth plastic dish about two inches (5 cm) high. You can also get a variety of mealworm feeders especially for this purpose. These can be useful if you want to limit the mealworms to specific birds, like bluebirds or chickadees instead of feeding every greedy starling for miles around. (Guess what happened to my mealworms???)
Dried vs Live Mealworms
Is it better to feed live mealworms or dried ones? That probably depends on the season. Mealworms have hard outer shells made of chitin that makes up most of the insect when dried. The crunchy shells are hard for young birds to digest and may be less appetizing to any birds in the warmer months when there’s plenty of juicier bugs to be had. But in winter when birds need high calorie foods to stay warm and insects are hard to find, a freeze-dried mealworm looks a lot more appetizing.
Some bird lovers spray the dried worms with a light coating of olive oil or soak them in very hot water for an hour or longer before putting them out. They say the birds seem to like them better that way.
Dried mealworms can be stored the same as bird seed; live mealworms should be stored in a cool but not freezing spot (in the fridge maybe?) to keep them from developing into beetles.
If you are going to be keeping live mealworms in your fridge for more than a couple of weeks, take them out for a few hours so they can eat and get fresh air. Be sure discard any that are discolored or dead and don’t feed those ones to your birds as they could cause food poisoning.
Squeamish about live worms? Fear not. Live or dried, mealworms are not wet or slimy, don’t bite and aren’t poisonous. You can handle them with your bare hands or (as I did) with a scoop or wearing gloves.
What Are ‘Giant Mealworms’ and Should You Feed Them to Birds?
So-called giant mealworms, often sold as reptile food, are just regular mealworms with one important difference: commercial growers treat them with s-methoprene, a biochemical pesticide that acts like a juvenile growth hormone, preventing pupation and causing mealworms to grow larger. It’s available to licensed users under several different brand names.
S-methoprene is considered ‘slightly toxic’ (or ‘relatively non-toxic’, depending on which side of the industry you’re on) to birds. According to a paper given at the West Nile Virus Action Workshop 2000, birds may show symptoms such as slowness, reluctance to move, sitting, withdrawal, and in-coordination as quickly as two hours after consuming just 0.5mg/gram of s-methoprene.
These symptoms can last up to two days and would obviously make it much more difficult for affected birds to survive predator attacks.
Giant mealworms as bird food? NOT.
Waxworms and Super worms
Waxworms are actually the ivory-colored caterpillar form of the Greater Wax Moth Galleria mellonella. Unlike mealworms, they have a soft outer body, which makes them easier for baby birds to digest, and contain lots of moisture too. Waxworms are a great food to offer in springtime.
Waxworms are available online too, and can be stored in a cool place (50-55° F or 10-12° C) without feeding for three or four weeks.
Note: Waxworms are also treated with a biopesticide that stops them from maturing. I’ve been unable to pin down the exact chemical, but it seems likely to be Azadirachtin, which is a component of Neem oil. Neem oil is considered non-toxic to birds.
Superworms (sometimes called Kingworms, Morio worms or Zophobas) are the larvae of another type of darkling beetle, Zophobas morio. They look something like mealworms but are much bigger (up to 2.5 inches or 6 cm) and have a softer exoskeleton. They have six stubby legs and strong mandibles. (Yes, they do bite so don’t let your pets investigate them!)
Superworms won’t mature into if they are kept in a container with lots of other superworms and plenty of food.
This is another type of live feeder worm you can buy online.
A Worm to the Wise: Don’t Overfeed
Mealworms, waxworms and superworms are nutritious and tasty—birds of all kinds will devour them by the bucketful if you let them, but you shouldn’t. Unfortunately they’re high in phosphorous, which means that digesting them results in a net calcium loss to the bird, leaving less calcium for healthy bones and egg shells.
If you’re feeding just one breeding pair and their chicks, 100 or so worms twice a day is plenty.
So, are you going to add worms to your feeding schedule? Which ones will you use? Let me know in the comments below.
Top Image: European robin eating a mealworm by Fsphil, CC by SA 3.0, via Wikimedia Commons